Railway traffic controlling apparatus



March 16, 1943. F, H. NICHOLSON ETAL 2,313,387

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept.- 4, 1941 gggvw ceed indication.

Patented Mar. 16, 1943 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Frank H. Nicholson and Township, Allegheny Our invention relates to railway traffic controlling apparatus, and particularly to automatic train controlling apparatus of the intermittent inductive type.

Intermittent inductive train control and cab signal systems ordinarily provide but one pro- The trend toward higher train speeds and longer trains makes the provision of an additional proceed indication desirable.

Accordingly, a feature of our invention is the provision of railway traffic controlling apparatus organized into a novel and improved intermittent inductive three-position train control and cab signal system.

Another feature of our invention is the provision of railway traflic controlling apparatus of the type here involved incorporating novel and improved means to eliminate the possibility of a false proceed indication.

Again, a feature of our invention is the provision of relatively simple and inexpensive apparatus for an intermittent inductive three-position train control and cab signal system.

Other features, advantages and objects of our invention will appear as the specification proresses.

To attain the foregoing features, objects and advantages of our invention we provide two trackway or roadside inductors in tandem on one side of the track at each control point or signal location along the railway. The two inductors of a control point are governed to different, conditions in response to different trafiic conditions in advance and in each ofsuch conditions two successive control influences are transmitted to a train carried receiver as the train passes such control point. Each such combination of two successive control influences is made distinctive so that each different traflic condition is reflected by a distinct combination of two succes sive control influences. In the particular form of the invention here contemplated; clear traflic condition is reflected by a combination of control influences in which the first of the two control influences creates a predetermined higher than normal electromotive force in a train carried receiver, and the second influence causes no change in a predetermined normal electromotive force in such receiver. Under approach traffic conditions in advance, the first transmitted influence of the combinatio creates the previously mentioned predetermined higher than normal electromotive force in the train carried receiver, but the second influence creates a predetermined less than normal electromotive force. Under stop or slow speed traflic conditions in advance, each of the two control influences of the combination creates the previously mentioned less than normal electromotive force in the train carrier receiver.

Harold W. Bryan, Penn County, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application September 4, 1941, Serial No. 409,492

6 Claims. (Cl. 246--63) Onthe train we provide signaling apparatus that includes a receiver having a winding and means to create an electromotive force in the winding, a group of control relays governed to different positions by the electromotive forces created 'in the receiving winding, and a cab signal and train controlling mechanism selectively governed to different positions by the control relays. The receiver is disposed for inductive relationship to the roadside inductors and the value of the electromotive force created in the receiver winding is governed by the char-' acter of the control influence transmitted by a roadside inductor so that at each control point the two control influences transmitted create two predetermined values of electromotive force in the receiver winding.

In the instant case, three predetermined values of electromotive force are provided, amely, a predetermined normal value, a predetermined higher than normal value and a predetermined lower than normal value. A first one of the control relays is adjusted for a pick-up electromotive force which corresponds to the higher than normal electromotive force and with a release electromotive force which corresponds to the lower than normal electromotive force. A second control relay is adjusted for a pick-up electromotive force which corresponds to the normal electromotive force and with a release electromotive force which corresponds to the lower than normal electromotive force. A third control relay is a stick relay controlled by the first and second relays.

The first and second relays are connected to the receiver winding over a receiving circuit having alternative circuit paths which are interlocked in a novel manner to cause the three relays to respond in a distinct arrangement for each of the difi'erent combinations of two control influences. transmitted by the two roadside inductors of a control point. The interlocking of receiving circuit paths for the control relays is also such as to eliminate a false arrangement of the relays being effected due to a wrong control influence. We use these three control relays to selectively govern the different positions of a cab signal and of a brake controlling magnet, so that preselected positions of the cab signal and brake controlling magnet are established for each particular combination of control influences, that is, for each different traffic condition.

We shall describe one form of apparatus embod-ying our invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Figs. 1 and 2 when taken together are a diagrammatic view showing one form of apparatus embodying our invention, Fig. 1 illustrating the roadside portion 1 are also disposed a short distance apart.

' of the apparatus and Fig. 2 illustrating the train carried portion of the apparatus.

Referring to Fig. 1, the reference characters Ia formed by the usual insulated rail joints with successive track sections of a signal system. The two full sections D--E and E-'F,together -with the adjacent ends of the two adjoining "sections only are shown since these are sufiicientt'o illus trate the principles of our invention Each section is provided with a track circuit whichcomprises a source of current, such as a battery 1'0,"

connected across the rails at one end of the sectiori anda track relay designated by'the reference character TR, plus aprefix' corresponding to the ,location connected across the rails at the other end of the section. Each section isalso provided with a line circuit whichincludes a'line relay designated by thefreference character DRi plus a prefix corresponding toits location, and which circuit is controlled by traflic' conditions in the section next in advance. For'example, the line circuit for section E-F includes a line relay EDR and is controlled over front contact'll of track relay FTR for the section next in advance of section E F. The line'circuit for each of the other sections is of a similar. arrangement.

Automatic wayside signals,'one at the entrance end of each track section, are'preferably provided, such signals being identified by the reference: character S plus 'a prefix corresponding to the location. The type of wayside signal is immaterial and any standardtypeof three-p c isition l ma be s d Ea h Su s a 3 1- trolled by circuits governed by f the track: and line circuits of the associated secticn but such signal control and" operating'circuits are not shown since they would 3 be in accordance with standard practice and form no part of our present invention. It is 'suificient ufor the present application to point ont .thata Wayside signal is set 'to'display astop indication when the section immediately in advance is occupied, isset to display an approach signal indication when the immediate section advance is unoccupied and the second section in advance is occupied, and is set to display a clear signal indication when at least the two sections next in advance are unocup d. w

Trackway or roadside elements designated by the reference characters Al and A2, respectively,

plus a. prefix corresponding to the location are provided for each section. These two roadside elements for each section are installed on one side of the track in a tandem arrangement and are preferably installed just to the rear of the entrance end of the section. The two elements These trackway elements may take any one of several different forms and are preferably all alike. One form of trackway element that may be used is that of the roadside inductor disclosed in Letters Patent of the United States No. 1,843,477, granted February 2, 1932, to Paul N. Bossart, for Railway traific controlling apparatus. As shown in Fig. .1, the roadside elements are of the inductor type of the above Bossart patent and it is sufficient for this application to point out that inductor DAI, for example, comprises a magnetizable core Hand a winding l3 mounted thereon, 'core'lZ having topoles lZa. and I21). As stated hereinbefore, each of the other induc'tors is of a similar construction.

section D-E, inductor DAI which is the first inductor passed by a train about to enter the associated section DE when moving in the normal direction of traffic, is controlled over a circuit that extends from the right-hand terminal of its winding {3; wire it, front contact I5 of track relay-DTR,wire it, a condenser l1 and to the left-hand" terminal of winding l3. The second inductor-DA! iscontrolled over a circuit that extends'frorn oneterminal of its winding l3,

winding l3 of the second inductor DA2 isfshort circuited' when both the associated track and line relays 'are pick'edup. Hence undercl'ear trafiic conditions in advance of'the control point Dan d both track relay DI'R and line relay DDR/ are picked up, the'windings of both inductors DAI and. DA2 are short circuited,'condenser I! being interposed in the circuit for inductor DAL V on: der approach trafilc conditions inadvance of con trol point D and track relay DTRis'picked up and line' relay DDR4 is released, thewinding of the first inductorDAi is short circuited'as before and the winding of the'second inductor DAZ' is open circuited. Under stoporslow speed'tram'c conditions in advance of control'point D and tracltrelay DTR is released, the windings of both inductors DAI" a'ndDA2 are-open circuited; The circuits for the other pairs'of inductors are controlled in a manner similar'to that just de-v scribedforin'ductors DAI and DA2 and'wilhbe readily understood by an inspection of Fig; 1.i'

Since the reluctance of each roadside inductor is varied according as'its winding is open 'circuited or short circuited, and is further varied according as its circuit connection includes a condenseror not, it follows that each pair of roadside inductors of Fig. 1 is adaptable of being conditioned to create different combinations of two control influences taken froina group of three influences. The manner whereby the dilierent combinations of two control influences efiected by each pair of roadside inductors according todifierent trafiic several different forms and the form shown in Fig.

2 is that disclosed in'the aforementioned Bossart Patent No. 1,843,477 and to which patent refere shoe is made for a full description of such atrain carried receiver. It is suflicient for this applica tion to point out that receiver AT comprises a primary winding 24 and a secondary winding 25 mounted on a magnetizable corestructure having two poles 22 and 23. This core structure is analogous to the electric circuits of the wellknown Wheatstone bridge, the air gaps 28 and 29 forming two arms of the bridge, and the air gap between poles 22 and 23 and the air gap 3| forming the other two arms of the bridge.

Receiver AT is mounted on the train in a posiron. th ts oles 2. and 2. pass o e he poles or the roadsideinductors with proper clearance. Thus when poles 22 and 2-3 are above the two poles of a roadside inductor the air gap between the poles 22 and 23 is varied by the core of the roadside inductor and. the Wheatstone bridge arrangement of the core of the receiver AT is influenced. The extent of such influence on the receiver AT depends upon the closed or open circuited condition of the windin of the roadside inductor and also upon the presence or absence of a condenser in the inductor circuit. Thus as here shown there are three possible influences impressed upon the receiyerAT, one when the roadside inductor winding is open circuited, a second one when the inductor winding is short circuited and a third influence when the inductor winding is short circuited through a condenser.

Primary winding 24 is constantly supplied with alternating current from a generator GI, the circuit for winding 24 preferably including a condenser 26 by means of which the circuit is tuned to resonance atth frequency of the current supplied bygenerator GI. An electromotive force is; induced in secondary winding 25 due to the alternating current supplied toprimary winding 25 by generator G5, the value of such electrornotive force being governed of course by the condition of the core structure of the receiver AT. The parts are so proportioned that normally, that is, when-receiver AT is not in a position for inductive influence by a roadside inductor, a predetermined normal value of electromotive force isinduced in secondary winding 25.. Such normal value of electromotive force is not changed when the receiver AT is disposed over an inductor whose winding is short circuited with no condenser included in the connection. That is to say, the normal value of electromotive force induced in secondary winding 25 is not changed by the control influence efiected at each second inductor of each tandem of the roadside inductors when such second inductor is short circuited. The electromotive .force induced in secondary winding 25 is increased to a predetermined higher than normal value when the receiver AT is disposed above a roadside inductor whose winding is short circuited through a condenser. That is to. say, the electromotive force induced in secondary winding 25 is increasedto. a predetermined higher than normal value by the control influence effected at each first inductor of each pair of roadside inductors when such first inductor is short circuited. The electromotive force induced in secondary winding 25 is reduced to. a predetermined lower than normal value when -the3receiver AT is disposed above an inductor whose winding is open circuited. That is to say. a predetermined lower than normal value of electromotive force is created in secondary winding 25 at each roadside inductor whose Winding is open clrcuited.

Secondary winding 25 of receiver AT is connected to control relays A and AR by a receiving circuit including alternative circuit paths, and relays A and AR are conditioned to different; positions according to the electromotive forces created in winding 25 by the particular combination of two control influences effectedby the two inductors of a control point, the position of relays A andAR effected at a control point being retained until the train reaches the next control point. In order that relays A and AR may be thus. conditioned by the normal, higher than normal and lower than normal electromotive 3 forces created in winding 25, relay A isv adjusted for a pick-up electromotive force that, corresp nds to the higher than normal electromotive force and with a release electromotive force that corresponds to the lower than normal electrometive force, while relay AR is adjusted for the pick-up electromotive force that corresponds to the normal electromotive force and for a release electromotive force that. corresponds to the lower than normal electromotive force. Relays A and AR in turn control a two winding stick relay AP, the pick-up circuit of which includes its top winding 32 and front contact 33 of relay A, and the stick circuit of Which includes its lower winding 3.4,, its front contact 35 and back contacts 36 and 31 of relays AR and A, respectively. The alternative circuit paths for relays A and AR and the manner whereby the relays are controlled by the electromotive forces created in winding 25 will also appear when the operation of the apparatus is described.

A three-position cab signal CS is selectively controlled by the, control relays A, AR and AP.

A brake controlling magnet valve MV is also preferably provided and governed by the control relays A, AR and AP. The brake controlling mechanism governed by the magnet valve MV is not shown for the sake of simplicity since it may take any one of the several well-known standard forms of such mechanism and its specific construction is. not a part of our invention. It is sufiicient for the present application to point out that such brake controlling mechanism may comprise a warning whistle and a brake controlling valve and that when the magnet valve MV is energized the warning whistle is silent and thej'brake controlling valve is conditioned to effect the release position of the train brakes, but that when magnet valve MV is deenergized, the warning whistle is sounded and the brake controlling valve is operated to initiate an automatic application on the train brakes.

The train carried apparatus also preferably includes the usual acknowledging means which as shown in Fig. 2 comprises a source of air supply, a manually operable valve AV, a pneumatic relay PV and. a stick relay SP. The valve AV is a manually operable two-position valve and when its. handle 46 is set at a normal position, that is, the position illustrated by the solid lines in the drawing, a valve. 4.1 is set to connect an acknowledging reservoir 48 to the train air supply and pressure is stored in reservoir 48. When handle, 46 is moved to the position illustrated by the, dotted line in the drawing, the train supply is shut olT and reservoir 48 is connected to the diaphragm chamber of the. pneumatic relay PV which causes the relay PV to be actuated and close a circuit. controlling contact 49. Relay SP is a. two-winding relay, its. pick-up winding 50 being energized over an obvious circuit including contact'49 of relay PV, and its second winding 5|, being energized by a stick circuit extending from, terminal B of a convenient source of ourrentsuch as a battery not shown, over back contacts. 31,, 36 and 52 of relays A, AR and AP, respectively, front contact 53 of relay SP, winding 5| of the relay and to terminal 0 of the same source. of current. Thus relay SP is picked up due to manual operation of valve AV, and is re t ained picked up as long as the control relays A, AR and AP are released. Relay SP controls the circuits for magnet valve MV as will shortly appear. I r

J In describing thef'o'peration' ofthe appararufs weshall assume that in Fig. 1 a train indicated conventionally at TN occupies the section next in advance of section EF with the result that both inductors FA! and FA2 associated with such tion condition in a manner to later appear, that is, the apparatus of Fig. 2 occupies the position shown in the drawing. Under such clear signal indication condition of the apparatus of Fig. 2, it is to'be observed that relay A is connected to the winding over a circuit path that includes its own front contact 54, with the result relay A is held picked up by the normal value of electromotive force created in winding 25, it being recalled relay A is adjusted for a release electromotive force that corresponds to a predetermined lower than normal value of electromotive force. Also it is to be observed that stick relay AP' is picked up over its pick-up'circuit including front contact 33 of relayA. Furthermore, with relays A and AP picked up, an operating circuit is formed for signal CS and also for magnet valve MV. The circuit for signal CS extends from terminal B over front contact 38 of relay'AP, front contact 39 of relay A, lamp G and terminal C, and lamp G is illuminated to cause the display of a green light for a clear signal indication. The circuit for magnet valve MV includes terminal B, front contact 38 of relay AP, frontcontact 39 of relay A, a second front'contact 43 of relay AP, back contact 44 of relay SP and winding of magnet valve MV to terminal C, and mag net valve MV is energized to effect the release condition of the train brake controlling mechanism.

-We shall next describe the operations of the apparatus of Fig. 2 when the train on which such apparatus is mounted moves through the track sections DE and E-F of Fig. 1 with the train TN occupying the section next in advance of section E F. At control point D, the receiver AT on passing over the first inductor DAI inductively receives'a control influence that causes the predetermined higher than normal electromotive force in winding 25 and control relay A is retained energized and picked up since such high.- er electromotive force energizes relay A to a higher degree. At the second inductor DA2, the

control influence transmitted to the receiver AT causes no change in the electromotive force created in winding 25 and relay A remains picked up by the normal value of electromotive force. Consequently the clear signal indication condition of *the train carried apparatus remains in effect asthe'traingpasses through the section D-EJamp G being illuminated to display a clear cab signal and magnet valve MV being energized to hold the train brake controlling mechanism in its release position.

When receiver AT passes over the first in-' causes the predetermined'less than normal elec tromotive force to be created in secondary windf ing 25 because inductor EAZ is open circuited with the result that relay A is released. Stick relay AP-is nowretained energized over its stick circuit including back contacts 31 and 36 of' relays A and AR, respectively, and control relays A and AR are connected in series to the winding 25 by a circuit path extending from the lefthandterminal of winding 25 over front contact 55 of stick relay'AP, winding of relay AR,"back contact 56 of relay A, winding of relay-A and to the right-hand terminal of winding 25. Thus as soon as the receiver AT 'passes'off inductor EA2 and the normal value of electromotive force is induced in secondary winding 25 and applied to relays A and AR in series, therelay ARis picked up and the relay A remains released due to their respective pick-up electromotive force s. With control relay'i AR picked up opening' back contact 36,the stickcircuit for relay AP is opened and relay AP is immediately released; Since front contact 51 of relay AR serves to shunt front contact 55 of relay AP, the two relays A and AR remain connected in series to winding 25 so that relay AR is picked up and relay A is released due to the normal value'of electromotive force. With relay AR picked up and re lays A and AP released an approach Operating circuit is formed for signal CS and magnet valve MV, the operating circuit for signal CS extending from terminal B over back contact 40 of relay AP, front contact 4! of relay AR, lamp Y and terminal C, and lamp Y is illuminated to cause signal CS to display a yellow light'for an approach signal indication. The magnet valve circuit includes terminal B, back contact 31 of relay A, front contact 58 of relayAR, back contact 59 of relay AP, back contact 44 of relay SP, winding of magnet valve MV and terminal Cl It follows that an approach cab signal is displayed and magnet valve MV is energized while the train traverses track section "'ff When the receiver AT passes over the first inductor PM at control point F, the control in fluence transmitted to the receiver AT causes the predetermined lower than normal electro motive force to be created in winding 25 and relay AR is released, it being recalled that relay AR is adjusted for a release electromotive force which corresponds to such lower than normal value of electromotive force. At the'second 'inductor FAZ the control influence transmitted to the receiver AT also causes the predetermined lower than normal value of electromotive force to be created in winding 25. With relay AR'released the control relay A is ccnnectedto wind ing 25 by a circuit path extending from the left hand terminal 'of winding 25 'over back contact 60 of relay AR, a resistor 5|, winding of relay A and to the right-hand terminal of winding 25' Relay A is not picked up by the normal valuet'ifelectromotive force created in windin'g'25 when the receiver passes ofithe roadside inductor due to the high pick-up electromotive force provided" for relay A, the resistor Bl interposed iri-the circuit path aiding to prevent relay A from being picked up by such normal value of electromotive force.

from terminal'B over back contact 40 of relay AP, back contact '42 of relay AR and lamp R to terminal C, and lamp'R is illuminated to cause With the three control relays A, AR and AP all released an operating circuit is formed" 'deener'gized and to acknowledge the slow speed signal indication and reenergize the magnet MV the operator would actuate handle 46 to its dotted line position and actuate the pneumatic relay PV and cause the picking up of the acknowledging relay SP. Relay SP on picking up closing front contact 45 completes an alternative circuit for energizing the magnet valve to forestall an automatic brake application. Hence a slow speed cab signal indication is displayed by the apparatus of Fig. 2 as the train on which it is mounted moves into the section already occupied by the train TN, and an automatic brake application is initiated unless the operator acknowledges such slow speed indication.

Assuming that with the slow speed signal indication condition established for the apparatus or Fig. '2 and the train on which it is mounted encounters a control point at which an approach tra'flic condition is reflected by the roadsideinductors, that is, a control point similar to control point E of Fig. 1, the higher than normal value of electromotive force is created in winding 25 at the first inductor because its winding'is short circuited through a condenser. Such higher than normal electromotive force is efiective to pick uprelay A which is connected to winding 25 over back contact 60 of relay AR. Relay A on picking up connects relay A to winding25 over the circuit path including its own "front contact 54 so that the relay is held picked up after the receiver passes off such first inductor.

' Relay A on picking up also closes front contact 33 and completes the pick-up circuit for relay AP and that relay is picked up. Since at such approach control point the second inductor is open circuited, relay A is released when the receiver AT passesover the second inductor due to the, lower than normal electromotive force created in winding 25, and with relay A released and relay AP picked up, relays A and AR are con; nected inseries to the winding 25 so that relay AR is picked up by the normal electromotive force created in Winding 25 when the receiver passes oi the second inductor. It follows that the approach cab signal indication condition is established for the apparatus of Fig. .2 at such approach control point of theroadside apparatus.

Again assuming that the slow speed'indication condition exists for the apparatusof Fig. 2 and the train encounters a control point suchas con- ,trol point D of Fig. 1 and at which the inductors are set to reflect a clear traflic condition, relay-A is picked upi'n response to the higher than nor-- malvalue of electromotive force created by the control impulse transmitted by thefirst inductor and relay A is then retained picked up by the no change in the normal value of electromotive force effected by the control impulse transmitted at the second inductor, and consequentlythe clear siga nal indicationfcondition of the'train carried apparatus is established.

In the event the approach signal indication condition exists for'the apparatus of Fig. 2 and the train encounters a control point at which the inductors are set to reflect clear trailic condition,

ing 25 and relay A is picked up by the higher than normal valueof electromotive force created by thecontrol impulse of theflrst inductor. Relay A on being picked up to open back contact 55 and close front contact 54 disconnects the control relay AR and connects its own windingto winding 25 so that relay AR is released and relay A is held picked up. At the second inductor the control impulse is such that no change is made winding 25, and relay A remains picked up and consequently the clear signal indication condition is'established.

In case the train carried apparatus is set at the clear signal indication condition and the train encounters a control point such as location F where the inductors are conditioned to reflect a stop or 'slow speed traffic condition, relay A is released at the first inductor due to the lower than normal value of electromotive force created in winding 25. Relay AP is retained energized over its stick circuit and relay AR is picked up by the normal value "(if electromotive forces during the interval the receiver is passing from the first to the second inductor. At the second inductor relay AR is released due to the lower than normal value of electromotive force created in winding 25 and consequently all three control relays A, AR and AP are released as the receiver passes on the second inductor and the slow speed signal indication condition is established for the train carried apparatus.

From the foregoing description it is to be seen that the picking up of a control relay A or AR to establish either the clear or approach signal indication is effected only when the proper preselected combination of two successive control influences are received and consequently the establishing of a proceed cab signal by a wrong control influence is eliminated. Furthermore it is clear that we have provided simple and inexpensive railway tr'affic controlling apparatus organized into a novel intermittent inductive threeposition cab signal and train control system.

Although we have herein shown and described only one form of railway traffic controlling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described cur-invention, what we claim is:

1. Railway traillc controlling apparatus comprising; traffic controlled roadside meansoperable to a clear, an approach and a slow speed condition; said ineans including two spaced inductors with each inductor constructed to transmit either one of two different control influences and said means arranged for the two inductors to transmit adiifere'nt combination of two control influences for each of said conditions. a train carried receiver having a winding and means for creating an electromotive force in said winding, said receiver mounted for inductive relationrelays A andAR are connected in series to windship to each of said inductors tocreate a different predetermined value of said electromotive force for each or said control influences; train carried relay means connected to said winding and. operable to a clear, an approach and a slow speed position in response to the two successive electromotive forces created by thecombination of control influences transmitted by the clear, approach and slow speed conditions respectively of the roadside means; and a cab signal controlled by said relay means to display a clear, an approach and a slow speed signal according to the clear, approach and slow speed positions respec tivelyof the relay means.

2. Railway traffic controlling apparatus comprising, roadside means including a first and a second inductor in tan em; each or said inductors comprising a magnetizable core and a winding mounted thereo-n'and adaptable ofeffecting a different control influence according as its Winding is short circuited through a condenser, is short circuited or is open circuited; traific controlled means to control the connections of said inductor windings to effect a distinctive combination of two control influences for clear, approach and slow speed traflic conditions respectively; a train carried receiver having a winding and means to create an electromotive force in its winding, said receiver mounted for inductive relationship to said inductors to create a difierent predetermined value of said electromotive force for'each of said control influences; and train carried signaling apparatus connected to said rec'eiver winding to display a clear, an approach and a slow speed indication in response to said clear, approach and slow speed combination of control influences respectively. I I

3. Railway trafiic controlling apparatus comprising, a pair of roadside inductors at each of a plurality of different control points along a railway, the inductors of each pair arranged in tandem and each inductor comprising a magnetizable core and a winding mounted thereon and adaptable of transmitting a different control, influence according as its winding, is short circuited through a condenser, is short circuited or is open circuited; traiflc controlled means at each said control point to control the connections of the windings of the inductors at the same control point to effect a distinctive combination of two control influences for clear, approach and slow speed trafiic condition respectively, atrain car ried receiver having a winding and means to create an electromotive force in its winding, said 7 receiver mounted'for inductive relationship to said roadside inductors to create a differentfpredetermined value of said electromotive force-for each of said control influences; and train cara slow speed indication in response to the electromotive forces created by said clear, approach and slow speed combination of control influences respectively transmitted at each of said control points.

7 4. Railway trafiic controlling apparatus comprising, a first and a second inductor disposed intandem at a control point along a railway; each of said inductors comprising a magnetizable core and a. windingmounted thereon and adaptable of transmitting a different control influence according as its winding is short circuited through a condenser, is short circuited or is open circuited; traffic controlled means at said control point to short circuit the winding of the first indifferent combination of two electromotive forces in the receiver winding in response to the control influences for said clear, approach and slow speed traiflc conditions of the inductors, and train carried signaling means connected to said receiver winding operated to a clear, an approachand a slow speed signal condition in response to the atla es clear, approach and, slow1speedcombination of electromotive forces respectively." a V 5. Railway traffic controlling apparatus com p sin a first and,-a;s. co d roa ide nd t r at each of a plurality of control points along a railway, the inductors at each control poin dis posed in tandem along one side of the track and each inductor comprising a magnetizable core and a winding mounted thereon and adaptable oi transmittin a high,;a no change or a low control influence according asthe inductor winding is short circuited through a condenser, is -short cir; suited or is open circuited, respectively; means at each of said control points to short circuit the winding of the first inductor through a condenser and to short circuit the winding of the second inductor, to short circuit the winding of the first inductorthrough a condenser andto. open circuit the winding of the second inductor, andto open circuit the windings of both inductors under clear, approach and slow speed traflic conditions respectively in advance ofsuch control point; and train carried receiving means including a winding and acurrent source to create an electromotive force in the winding and said receiving means differently responsive to such high, no change and low control influences and disposed to be successively influenced by said inductors as the train passes a controlpoint to display a clear, an approach and a slow speed signal indication in response to the different combinations of two control influences effected under clear, approach and slow speed trafiic conditions respectively.

, 6. Railway traific controlling apparatus comprising, a train carried receiver having a winding and. meansfor creating a normal electromotive force in'said winding, a first and a second train 40):. 'ried signaling apparatus connected to said re- 7 ceiver winding to display a clear, an approach and carried relay, said first relay adjusted for a pre;

determined higher than said normal pick-up eleQ- i tromotive'force and for a predeterminedlower than said normal release electromotive forcejsaid f second relay adjusted for a pick-up electromotive force corresponding to said normal electromotive. force and for said lower than"normal release" electromotive force, a stick relay; said first relay connected to said receiver winding either ove'r a path including aback contact of said second relay or over a path including "its own front contact,' said first and second relays connected in'series to said receiver winding either over a path in- I cluding a front contact ofsaid stick relay and a back contact of saidlfirst relay or a path includ inga front contact of the second relay and said, back contact of-the first relay, said stick relay providedwith a pick-up circuit in'cludin ja front contact of said first relay and a stick circuit in cluding' a back contact of each of said first and secon-drelays, a three-position cabfisignal 'se'le'c-n tively controlled as to its position .by'said first and second. relays, and traffic controlledroadsida means disposed for inductive relationshipto 'said 1 receiver and efiective to successively: create in said 1 receiver windingsaid-high and said normal electromotive forces to'p'ick up=.the first and-stic k, relays under clear traffic condition, tosuccessively create in the receiver windingsaid high and said low electromotive forces to pick up said second relay under approach traflic condition,- and tosuccessively create in the receiver winding two said low electromotive forces toLrelease both the first and second relays under slow. speed. trafiic f condition. l I i I we 7 q v FRANKHJNICHOLSON; i Y i L R LP W- rA 

